Automatic telephone system



filed Feb. 2, 1921 m RE J E GARDNER AUTOMATI C TELEPHONE SYSTEM Aug. 31 1926" UhnEEard'nEr I Patented Aug. 31, 1926.

amt stains meta JOHN E. GARDNER, O1? CHICAGO, ILLINOIS, ASSIGNQR, BY MESTTE ASSTGNMENTS, TO

AUTOMATIC ELECTRIC INC,, 033 CHIGAGO ILLIHOIS, ACORPOPUATKON OT DELA- WARE.

AUTOMATIC TELEPHONE SYSTEIVI.

Application filed February 2, 1921. Serial No. 441,991.

The present invention relates in general to automatic telephone systems, but is more particularly concerned withthat'type of automatic s stem in which rotar connector switches are used by calling subscribers to complete connections tocalled lines. Connectors of this type, as is well known, are adapted to picl: outan idle line in a group of lines or if all the lines in a group are busy to notify the calling subscriber that the number called is busy. 7

An object of the invention is to so arrange the circuits of a connector of this type that the testing of each line which was formerly done by means of two test wipers is now accomplished by means of one- The particular manner in which this and other results are accomplished will be described fully hereinafter reference being had to the accompanying drawings.

Referring now to the drawings, in Fig. 1

is shown an automatic substation A having a rotary line switch C of well known construction individual thereto. The line switch C in common with a plurality of other similar line switches have access to rotary connectors one of which is shown at H. These connectors are of the Strowger type having the usual set of 100 bank contacts arranged in ten rows or levels. They have access to subscribers lines similar to the one shown at A, one of which is shown at A. 4

in Fig. 2 is shown the test bank and private normal conductor leading from each test coiitact, these being certain circuit'arr: nggenients which are necessary for the op-v oration of the rotary connector switch shown at H.

in order to facilitate the description the invention has been shown applied to an isolated P. A. X. or private automatic exchange but it will be readily apparent that it may be used in a large auton'iatic exchange wherein a call is made through a plurality of selector switches and a connector switch.

Having briefly, described the apparatus us d in the system, the operation of the same will now be explained in detail. For this purpose it will be assumed that the subscriber at substation A desires to call the subscriber at substation A andthat the lat ter substation is of the straight or private line type. i I iWb-en the receiver removed at eats relay 15 and the stepping magnet 17 in series, and at its armature 21 connects the test wiper 31 to the above circuitat a point midway between the switching relay and the said stepping magnet; The operation of the line switch G now depends upon whether or not-the trunk line with which its wipers are associated is or is not busy. If busy, there will be aground potential present on the test contactengaged by the test wiper 31. The switching relay 15 willbe short circuited and the stepping magnet 17 being supplied with direct groundby way of. the said test wiper will operate as a buzzer to advance the wipers 30-32, inclusive, step by step in search of anidle trunk line.v However, in the present case it will be assumed that the trunk linewithwhi ch the'switch wipers were engagementwhen the receiver was removed at substation A was idle. -Under these con ditions, upon the venergization of the line relay 16, the switching relay 15 will be energizedimniediately afterwards in series with the stepping magnet17. It may be stated at this point that the switching relay is of very high resistance so as to prevent the energizw tion of the stepping magnet 1'? in'series with it. Upon operating, relay 15 cisconnects the line conductors 11 and 12 of the calling substation from the winding of the line relay 16 and from ground, respectively, and extends themby way of armatures 23 and 25, wipers 30 and 32, bank contacts 3e and 36, nor mally closed springs controlled by relay 50, and through the upper and lowr windings .f the line relay 51 of the connector H. The line relay 51 willbeenergized over the line circuit and upon attracting its armature 73 completes the circuit of the slow acting release relay 52. Upon energizin this latter relay at armature 7'5 prepares the operating circuits of the connector H and at armature 74 places'ground on release trunk conductor 121 thereby establishing a holding circuit which extends by way of bank contact 35, test wiper 31', armature 24 and its front contact, winding of the switching relay 15, and the win-dine; ofthe )D'lll n a net 1? to H T 1 L in 1 i battery. will he or} that this tacts in the banks of. connector switches which have access tothe line of the substationA whereby the said line is protected.

from intrusion in the well-knownmanner. j The calling subscriber a't substation' A may now operate his calling device in" accordance with the first digitof the d'esired ,7

number thereby producing a seriesof interruptions in the line circtiit of relay 51' which operates in response thereto. At each retraction'of its armature 7 3 the line relay 51 completes a circuit .which extends from ground by way of armature 7 3 and its'back 7 contact, armature 7 5 and its frontcontact,

off normal springs 80 and 81,1windingof the slow actingseries relay53, and through the winding of the vertical magnet 125' to battery. Theabove is'the circuit'over which the first impulse to the vertical magnet is 1 sent. Upon .the first vertical step of the switch shaft the off normal. springs are shifted and the remaining impulses to the vertical magnet traverse a new circuit which is the same as'vthe one previously traced except that it includes the off normal springs 80 and 82, and armature 83 and its frontcontact, relay 53 being now energized. The vertical magnet 125 operates to raise the switch wipers 14:0142, inclusive, step by. step 'untilthey ware placed opposite thelevel of'bank contacts inwhichiare located the contact set associated with the line of the'substation A. The slow acting relay53 which is energized in series with the vertical {magnet maintains its armature attracted throughout the vertical operation of the switch and atthe termination of their vertical movement deenergizes and transfers the operating circuit to the rotary magnet 126.

. The calling subscriber may now operate his calling device in accordance with the last digit .of the desired'subscr ber s numberf A series of impulses are thereby produ'ced in the circuit of the line relay 51 which retracts its armaturea corresponding number of times, each time sending an impulse of current over the following circuit: ground by way'of armature 73 and "its back L contact, armature 75 and its front contact,-

of" normal springs and'82, meanness and its back contact, through the winding of the series relay 54, back contact'andnrmature 101, back contact and armature 94, armature li and its back contact, and thence lthrough the winding'o'f the rotary magnet 126 to battery. The slowiacting relays 5'41 and 58 are energized in response to placed; in engagement with the set of bank contacts in which is terminated the line of the subscriber at substation A which we will assume are bank contacts 150-152, inclu sive'. The'slow 'a'cting relay 58 operates to conneettest wiper 141 to the test relays 56 ands? The operation oft-he connector H ncwdepends upon whether or not the line of 'substati-onA isbusy or idle. If busy, there willbe a direct ground potential pres 'ent ontest contact 151. A circuit is then colnpleted extending from ground on said testcon tact byway of test wiper 141, armatui 'e 105 and its front contact, armature .116 and its back contact, where the circuit di- Vides',onepath extending byway of the norma lly "closed springs controlled by relay 5 7 and throughthe said-"relay to battery,- the f other one extending by way of back contact and armature and through the winding of relay 56 to battery.- Relays 56 *and 57 wlll energize over this circuit. Under these circumstances rela y 56 is adjusted to attract its armature 94: before relay 5? attracts armature'loi, This adjustment is made so as to preyent'any false operation of'the rotary magnet at this tim'eand is'very easily attained in practice. Relay 56 upon energizing, establishesa locking circuit for itself at armature 98 which circuit'eiitends from groundon release trunk conductor 121 by way 'of'armature 93 and its front contact, normally closed springs controlled by relay 58, armature 116 and its back contact, back contact and armature 85, and through the winding of relay 56 to battery; Relay 56 at armature 'also places the busy tone on the lower heavy talking conductor thereby notifying the calling subscriber that the desired line is busy. Relay 56 as before mentioned, at armature 94 also opens a point in the rotary magnet circuit. Relay 57 upon operatingyestablis'hesa locking circuit for itself at armature 100 extending from ground on release trunk conductor .121 by way of back contact and armature 86, through resistance armature 100 and its front'contact, and through the winding of relay 57tobattery. The operation of relay 57, however, is without function at this time. The calling subscriber knowing that the desired line is inaccessible at this time will replace his receiver upon the switchhook thereby releasing the connector H and the line switch'C'in the well'known manner.

Having described the operation of the connector H when the called line was busy it will now beyassumcd that the line of the stances there willbe'no ground potential on test contact 151'and no circuit will be completed on test relays 56'and 57. Then following the deenergigization ot' the slow acting relay 58 a circuit is-completed extending from ground on release trunk conductor-121 by way of armature 93 and its back contact, upper winding of relay 59, upper winding of relay 60, back contact and armature 105,

test wiper 141, test contact 151, winding of the switching relay 160, and through the winding of the stepping magnet 162 to battery. Relays 160, and 59 energize over this circuit: however, due to a mechanical interlockingdevice controlled by the armature of the line relay 161 which is now normal, the switching relay 160 only attracts its armatures enough to disconnect the line of the subscriber at substation A from its normal battery and ground connections in the line switch G. Relay 6O uponenergizing, establishes a locking circuit for itself at armature 118, at armature 117 places ground on test wiper 1 11 through resistance *1, and at armatures 115 and 120 completes' the ringing circuit. Relayb upon energizing, establishes a locking circuit for itself at armature-109, and at armature 108 places direct ground on test wiper 141. When the relay 6O energizes ringing current is intermittently, projected over the line of the called substation A until the subscriber thereat responds. hen this occurs a path for direct current is provided over the line loop or the called subscriber through the upper winding of the ring cut oil relay 55 to battery. Relay 55 energizes over thiscircuit, establishes a locking circuit for itself at armature and at armatures 89 and 91 cuts ol'lthe ring and at the front contacts of these armatures finally completes the talking connection. Conversation may now be carried on between the subscribers at substations A and A battery being supplied to the calling subscriber from the windings of the line r -lav 51 and battery being supplied to subscribers will replace their receivers thereby causing the release of the connector H and. the line switch C. H the calling subscriber at substation A hangs up betore the called subscriber'only the line switch C will be released. This is accomplished in the following manner: upon the receiver being replaced the calling substation the circuit of the line relay 51 is broken and upon this relay"deenergizing, the circuit ofthe slow a'ctin'g'release relay52 is opener. Relay 52 upon retracting its armatures, removes ground from the release trunk conductor 121. Upon relay 51re tracting its armature and before the deenergization of relay 52 an impulse ol current is sent to the slow acting relays 541 and 58. Upon operating, re-

lay 58 series to remove ground through the upper windings oi? the relays59 and 60 from the release trunk conductor 121. Ground is therefore removed for a short interval from the release trunk conductor 121, the circuit of the switching relay 15 of the line switch C is thus broken and upon its deenergization the line switclrC assumes its normal position. Upcn'the deenergization of relay 58, ground is replaced on the release trunk conductor 121 over the following circuit; ground by way otfront contact and armature 108; armature 117 and its front contact, armature and its back contact, upper winding of the switching relay 60, upper winding of relay 59, back contact and armature 93, and thence to the release trunkconductor 121. In the above manner the connector H is prevented trom being released until the called subscriber replaces his receiver upon the switchhook. When the called subscriber hangs up, the back bridge relay 50. deenergizes and at armature 77 completes the release magnet circuit. Had the called subscriber hung up first the connector H would be released immediately upon the calling subscriber replacing his receiver upon the switchhook in a well known manner.

Having described the operation of the connector H when a connection is made with a straight line, its operation will now be ex plained when the subscriber at substationlr desires to call an operator who has several trunks listed on the same number. in this case, the connector H is adapted to select and'connect with an idle one of these trunks or it all are busy to notify the calling subs'criber of this fact. here there are a number of truuks listed under the same number the private normal conductor leading from each test contact has a resistance in it. This is shown diagrammatically in Fig. 2. The

7 last trunk of the groupyhowever, has its private normal conductor connected in the usual manner. The resistances R and R in the for the digit of the desired ninnber.w?.--

1 line relay 51 has in the usual manner controlled the operation of the vertical magnet 125m stepping the switch opposite the level of bankcontacts in whichis located the. dc sired groupof trunk lines.

The calling subscriber may nowoperate his'calling device for the lastdigit ofhis desired numberthereby producing a series wipers are rotated into'engagement with'the t "interruptionsin the circuitof the line relay 51 which deenergizes a plurality of times in response thereto. As before, at-

1 each retraction of its arm'ature73an impulse 141 through a resistanceof 500 ohms.

of current is sent to the rotary magnet 126 in series with the slow acting relay 54 and inmultiple with theslow acting relay 58. The rotary magnet 126-operates to rotate the switch wipers into engagement with the s'etofbanlts associated with the first trunkline of the group. The slow acting relay 5'8v operates to connect the test wiper 141 to the test relays 56 and 57. "If this-firsttrunlr line may be busy a ground potential will be present on test-contactengaged by test wiper The test relay 56 is so adjusted that it will not energizein series with 5,00"ohms. Aneuergizino; circuit for relay 57, however. is now effective extending from the grounded. test contact'engaged by test wiper 141, by way of the said-test wiper, armature 105 and its front contact, armature 116 and its back contact, normally closed springs controlled byrelay 57, and through the winding of said relayto battery. Upon energizing, relay 571 at armature 100 establishes a locking circuit for itself and at the same point breaks: its connection to the test wiper 141. It will be noticed that the locking circuit of relay I? has the resistance R included. in it. This provision ismade forthe reason that'it this resistance were not included in the locking circuit of relay 5?, relay 56 might receive a direct ground impulse and energize. However, this is not possible with the-resistance R in this circuit. By theoperation of relay 57 a circuit is completed extending tronr ground on release trunk conductor 121 by way of armature 86 and its back contact, front contact and armature 102, back contact and armature 94,'armature 119 and'itsrback' contact, and through. the ,winding of the" rotary magnet 126 to battery. Magnet 126- operates to rotate the switch-wipers one step into engagement with the secondltrunlcline of thegroup-and at armature 1'10 breaks the locking circuit of thetest relay '57 which deenergizes breaking the c ircuitot the rotary magnet 126 which deener zizes also. The

slow acting relay 58 is energized in'multiple with the rotary magnet and serves tormaintain the test wiper 141 in connection with the test relays 56 and 57. Should this next trunk line be busy. and provided it is not the last one of the group, ground potential will again be present en it through a resist magnet circuit, whichmagnet will operate as before to rotate the switch wipers another step and to cause the deenergization ofthe test relay 57. This alternate operation of relay 5 7 andmagnet126 will continue until an idle trunkline is. found or until the switch last trunk line of the group. Y Should this' trunkbe busy also direct groundpotential will be present on't'est contactengagedbythe testwiper 141. Relays 56 and57 will both be energized as in the first case described wlierein the call was made with-a straight or private line. 'Relay 56 upon opand uponthe switch wipers being yzotated into engra 'ement there will be'no circuit for either. ot thetest relays 56 and 57; Then tollowing the deenergization of the slow acting relay 58 a circuit for' the switching relays and '60. will be completed. Should this trunk line not be the last one of the group the private normal conductor. will of course have a resistanceot' 500 ohmson it The relay 59 is so adjusted that it will not energize in series with the switching relay of the called line switch and 500 ohms resistance. The relay-60, however, operates over a circuit extending from ground on release trunk conductor 121 by wayof armature 93 andits bac-kcontac t, upper'windin ot relay 50, upper windingozt the switching relay 60, back contact and-armature 105, test wiper. 141, testcontact of the selected trunk line, private normalcon'ductor through the 500 ohms resistance, winding ofthe switching relay and stepping magnet ofthe associated through a resistance of 500 ohms and should another connector switch attempt to connect therewith, the relay similar to relay 57 will be operated and this switch willbe caused tone on the callingsubto rotate into engagement with the next" trunk line; Upon the operation ofrelay 60 ringing current is intermittently projected lii obtained from the operator ring out off relay 55 is energized and the succeeding operations take place in identically the same manner as was hereinbefore fully explained,

test contact of the, associated line by way of the test wiper 141. Thus should another connector switch attempt to connect with this line both the relays similar to relays 5G and 57 in'this switch will be enerized and. a busy tone transmitted llOrtllG calling subscriber. i i

It will be seen from the above that this invention provides a rotary connector switch which accomplishes the same results with one test wiper as .was formerly done with two. v

Having fully described and ascertained the features of the invention, what is desired to have protected by Letters Patent will be pointed out in the appended claims. ll hat I claim as my invention is 1. In a telephone system, a calling subscribcrs line, an automatic switch associated therewith, a group of telephone lines having 'tern'iinals in said switch, means controlled by said calling subscriber for controlling said switch to connect with a line in said group, a pair of relays for'said switch, a single test wiper, means for energizing one of said relays by way of said test wiper when connection is made with one line in said group, .and means for energizing the other of said relays by way of said test wiper when connection is made with another line in, said group.

2. In a telephone system, lines of two classes, an automatic switch for connecting with said lines, test contacts for said lines, means in said switch effective when a line of one class is connected with for placing a certain busy potential on the test contact thereof, and means in said switch effective in case a line in the other class isconnected with for placing a different busy potential on the test contact thereof. 7

3. In a telephone system, lines of two classes, an automatic switch for connecting with said lines, test contacts for said lines, means in said switch effective when a line of one class is connected with for placing a certain busy potential on the test contact thereof, means in said switch effective in case a line in the other class is connected with for placing a different busy potential on the test contact thereof, said means comprising two relays, and means for energizing one or both of said relays depending on the class of line connected with.

4. In a telephone system, called telephone lines of two classes, a test contact for each line, an automatic switch having a test of said test contacts, a pair of wiper adapted to be connected withany one switch each for applying a diierent busy potential to testcontacts connected with, the second of said relays also having meansfor applying ringing current to the called line,

'SdlCl second relay operative when the called line belongs to one classandboth ofsaid relays operative if the called, line is of another cl-ass, means controlled by the first relay for making ineffective the busy potential applied by said second relay so that the busy potential applied is dependent on the class of the line called.

5. In a. telephone system, called lines of two classes, an automatic switch havingac- .cess to said lines,- a pairrof relays in said switch, means for energizing only one of Said relays when connection is made with on; of said lines to make that line busy, means for energizing the other of said relays when connection is made with another of said lines, and means operated by said other relay for making ineffective the busy potential applied by said first relay.

connected with a test contact of one kind of line for applying a busy potential to its test contact, and means in said switch effective When the switch is connected with a test contact of another kind of line for applying a busy potential of a different character.

7. In. a connector having lines and test contacts accessible thereto, means for placing test potentials on the test contacts of lines when the same are called and found idle, means in said switch for determining the values of applied test potentials, and testing means in said switch selectively responsive to such test potentials when lines are called and found busy,said potentials in the second case being applied to the test contacts of the lines called by other connectors.

8. In a rotary connector, a test wiper, test contacts accessible to said connector having two different test potentials on them, two relays in said connector connected to said test wiper in multiple when the same engages a test contact, both relays being responsive to one potential and only one relay being responsive to the other potential, and automatic operating mechanism in said connector controlled jointly by saidtwo relays.

9. In a rotary connector, a test wiper, testcontacts accessible to said connector having two different test potentials on them, two relays in said connector connected to said test wiper in multiple when the same engages a test contact, both relays being responsive to one potential and only one rcin said lay being responsive to the other potential,

a'motor magnet in said'switch having acircuit closed by contacts on oneofsaidrelays, and contacts on'the other of said relays for openingsaidclrcult. 1

10, In a rotary connector, a test wiper,

testcontacts accessible'to said Wiper, two

relaysin said connector operable when said wiper is in engagement with a test contact,

contacts on one relay forplacing a certain contact, a resistance, contacts on one relay for grounding said wiper through saidresistance, and contacts 'on theother relay for short-circuiti1ig saidresista'nce.

In a tel'eliilionesystem, a plurality of lines, automatic switching. mechanism for extending said lines. when cal-ling, an 2111-,

tomatic switch for extending connections to said lines when the same are called, individual testcontacts for said lines in the banks of said switch, means effective whenever any one of a certain plurality of'said lines calls for connecting a source of test potential to the "test contact individual to Y "the callingxline, and meansettective whenever any other line calls for connecting a source of test potential to the test contact individual to the calling line over a different circuit, whereby different test potentials are presentfi'on said test contacts when the corresponding lines'a're tested, and

testing means in said automatic switch selectively responsive'to said test potentials.

13. In a telephone system, a plurality of lines, automatic switching mechanism for extending saidlines when calling, an automatic switch for extending connections to said lines when the same are called, individual test contacts for said lines in the banks of said'switch, means for placing direct ground on the test contact of any one of a plurality of lines when such line is calling, and means for grounding-the test contact'of any other of said lines through a resistance when the same is calling. 1

l l. In 'a'telepl'ione system, individual and grouped lines, a cut-off relay 'indiyidua'l to each'line, a test contactindividual'to each line, a connection from "each cut-o-fi' relay to the associated test contact, resistances in'-' of line calling,

serted in'saidfconnectionsr-in the case' of all thegroupedlinesexcept the last line of each group-,.' and means effective when any line is calling for connecting a source of current to the associated test contact direct or through a resistance, depending on the kind overa circuit excluding the associated cut-off relay. o v .715. In a telephone system, a rotary connector, groups oflines accessibleto saidi connector, test contacts for said lines in the bank of said COIl11GCt0I,-Cllt-Ofi relays for the last lines-of the several groups connected direct to theirassociated test contacts, cut-oil relays for the other lines of said groups connected to their associated testcont'acts througlrresist'ances, and contacts' on each cut-off' relay for connecting a source of test potential to the associated test contact, either direct or through. the

associated resistance, if one is presenti 16. In a telephone system, called' linesr of two classes, an automatic-switch: for extending connections to any of said lines, a test contact for each: one of said lines, means forplacing a' busy condition: on the test contact of-aline' when a connection is extended thereto, and means in: said switch for Chang'- ing said busy condition providing said line is of arcertain; one of said classes.

17 111: a. telephone system, a group of lines, a cut-ofi. relayfor' each ofsaidylines,

a test contact for each of saidlines, a con nection from' each cut ofl relay to the asso- Vein-ted test contact, rcsistances-- inserted in said connections, means for energizing the cut-off relay of a line iIlRSBIiQS with: iiISaELS- soc-'iatedl resistance when the 'line is called, and means for'energizing'the cut-ofi' relay of line independent of its associated resistance when'the line is: calling, 1 '18. Ina telephone system, two kinds of lines, test contaotsfifor said lines, automatic switches for extending calls to or from said lines including "connectoirsfor extendingconnectionsto said line's, means for establishing distinctive busy.conditions on said test cont'acts in accordance with the kind of line when said lines are busy, means associated with the lines for setting up the distinctive busy conditionsif the lines-are call ingfand means in the co'imectors' for setting'up the distinctive busy conditions if the lines are being called.

Signed by me at Chicago, Illinois, this 15th day of January 1921.

i JOHN E. GARDNER. 

